Conventionally, when grinding the back of a wafer (back grinding) after a pattern forming process, a broad protective tape is first applied the surface of the wafer, parts of the protective tape protruding from outer peripheries of the wafer are cut off along the wafer peripheries, and a grinding process is carried out for the wafer, with the entire surface thereof protected by the protective tape, and suction-supported at the surface thereof by a suction cup. Thereafter, the protective tape, which is now an unwanted substance, is peeled and removed from the surface of the wafer.
A removing method using a peeling tape exists as means for peeling off the protective tape, and its outline is shown in FIG. 30. In this removing method, a peeling tape T with a stronger adhesion than a protective tape P is applied to the protective tape (unwanted substance) P adhering to the surface of wafer W. The peeling tape T is wound up while a peeling roller 40 is rolled over the wafer to run rightward in FIG. 30, whereby the protective tape P is peeled together with the peeling tape T as shown in phantom lines in FIG. 30.
In this case, the peeling tape T is wound with the curvature of the peeling roller 40. At a point where the protective tape P peel from the surface of wafer W, the peeling angle of the protective tape P to the surface of the wafer is a small angle close to zero, and a peeling force acts in a direction approximately perpendicular to the wafer W. As a result, where the wafer W is thin and weak, as shown in FIG. 31, the wafer could break at a point A.
Further, as shown in FIG. 32, a wafer W with beveling b formed by obliquely cutting off outer peripheries may be back-ground to a large extent reaching a level G of the beveling b. With this thin wafer W, as shown in FIG. 33, a protruding end Pa of protective tape P could droop and stick to the beveling b. In such a condition, it would be difficult to start peeling the protective tape P at that end. When the peeling tape T is wound up with the peeling roller 40 rolled along in this state, the wafer W could break with greater ease.
The above phenomenon in which the wafer is broken by a tape peeling force applied when the peeling tape is peeled occurs also when peeling the peeling tape applied directly to the surface of the wafer in order to remove, with the peeling tape, resist layer (unwanted substance) remaining on the surface of the wafer.
This invention has been made having regard to the state of the art noted above, and its object is to provide a removing method and apparatus for peeling and removing unwanted substances from wafers by using a peeling tape while avoiding the wafer being broken by a tape peeling force.